Apparatus for measuring speed of rotation.



PATENTED OCT. 29, 1907.

No. 869,442. I

W. D. LITGHFIELD. APPARATUS FOR MEASURING SPEED OF ROTATION.

APPLICATION FILED OUT. 6, 1903- mag.

MTNESSES:

fix?- UNITED H PATENT OFFICE.

WALTER D. LlTCHFIELD, OF SCllEN ECTADY, NEW YORK, Ab 'lGNOll TO GENERAL ELECTRIC NEW 1U iii.

APPARATUS FOR MEASURING'SPEED OF ROTATION.

No. 869,442. Specification of Application filed October 5 To all whom it may concern:

Be it known that I, WALTER D. Li'rcnnintn, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Apparatus for Measuring Speedof Rotation, of which the following is a specification.

This invention relates to apparatus for ascertaining the speed of rotation of shafts and the like and he] es-- pecial reference to dynanio-electric apparatus A common mode of doing this is by means of a rotation counter which registers the actual number of revolutions, and is held on the end of the shaft for some predetermined time, usually one minute. The dilliculty here is in keeping the load, and consequently the speed, constant during the interval of test, and the object of my invention is to provide an organized system of devices which shall automatically insure that the rotation counter will operate only when the load and speed are at some given value. This is accomplished by connecting the rotation counter to the rotating part of the machine under test by means of an electromagnetic clutch in circuit with one or more switches located at the loadindicating instrument or instruments, and also in circuit with an electrically-controlled timing mechanism whereby one or more operators stationed at the load-indicating instrument or instruments can close the switch or switches at the instant when the load is of a predetermined value and thus cause the rotation counter and the timing mechanism to be simultaneously operated only at such time or times and for so long as the switch (or all of them if more than one is used) remains closed. At the end of the test. the total number of revolutions registered by the rotation counter divided by the number of seconds registered by the timing mechanism will give the exact speed at the predetermined load. The test may extend over several minutes, but the device will operate only during those portions of the time in which the load was at the given value and the switch or switches closed. The invention is therefore of especial advantage in running speed curves where the load varies considerably. The switch or switches may be closed automatically by the load-indicating instruments, if desired; but I prefer to have them worked by hand, as the automatic closure complicates the system and makes it more delicate to keep in'order.

In the accompanying drawing, Figure 1 is a d iagrammatic representation of my systemf-Fig. 2 shows an automatic circuit-closer; and Fig. 3 shows a detail of the automatic circuit-closer.

The rotation-counter 1 may be of any desired pattern in which the rotations of aspindle 2 are registered by a counting-train 3. Connected with the spindle is one member 4 of a clutch, the-other clutch-member 5 Patented Oct. 29, 1907'.

being rigidly secured to the end of the shall. 6 or other rotating part of the machine whose speed is to be asccrlaincd. The axes of the spindle and clutch-members arc. oi courstnin line with the axis of the shaft. The clutch can be opci'at =d in any suitable way. I have shown a lever 7' fulcrumcd in an arm 8 on the counterframe. A spring 9 keeps the clutc 'incmber 4 nornially disengaged from the znoinbt and causes a Make-collar 10 to pre s against a stationary f ll on the frame of the l'OiltllOIl-tililllltll. 0n the lever is the armature L? of an electroonagnct 1 3, which when onergizcd acts to close the clutch and thereby couple the rotation-(puntcr to [litshaft.

Asuitnblc timing mechanism, such as a clock ii, is controlled in any desired manner by an clcctromagnct 15, so that when said magnet is nergized the clock is allowed to start, but is stopped again when the magnet is opcn-circuitcd. 7

At some convenient station or stations are arrangedload-indicating instruments, such as a volt anotcr l6 and aminetcr 17. At each instrument is a push button or switch 18. A source of electric current, such as a butwith the clectro-magnets l3, 15, the parts being proforably arranged in series.

The operation is as follows. of observer at each slation (loses the circuit by means of his swilrh 18 whenever and as long as his instrument shows thrpropcr reading. 'lln-rc will thcreiorc be a complete circuit only when all the instruuu-ius give the etn'rcci i'nd'ir'n tion, and when this occurs the olcciromagnvts wil be .cd, clntciiiugh shalt, and releasing tllP timing mechanic \lhen the circuit is broken by any one of the observers, thrclutch flies open and the bralm-collar l0, actir on the face ll, instantly stops the rotation counter. Simultaneously, the clock is arrested. At the termination of the run, the total number oi revolutions counted, dividcdby the revolutions per second under the proper load.

It is possilile to make the system entirely automatic, by using instruments which will operate also as oire closers when they indicate the proper load. Such an instrument is shown in Figs. 2 and 3, which illustrate a voltmeter or animcter having two needles 2O, 21 mounted on the arbor which carries the movable element. These needles are pressed by light springs, as indicated in Fig. 3, in opposite directions so as to be brought to rest in a normal condition against two stops 20", 20 carried by the arbor. Mounted in a slot on the voltmeter or wattmeter scale is a slide 22 composed of two sections insulated from one another, but movable as a unit in the slot. The sections have tongues which lie in the path of the needles 20, 21, and when the slide is shifted to any given point of desircd load both needles tery i9, is connected with said switch or switches and.

rotation Zi)ll!ll l' to tho rotating.

number of Seconds measured off by the cloclg'givcs 1hr will bear against the opposite protruding tongue so long as that load is maintained. When in this condition the circuit is completed through the clutch magnet 13, the two sections of the slide forming terminals of the clutch circuit. Thus so long as the needles hear on the tongues this circuit will he closed through the shaft on which the needles are mounted, but on either a decline or in crease of load one or the other needle will be shifted away from the tongue with which it engages, thereby opening the circuit and disconnecting the counter.

in accordance with the patent statutes, I have described the principle of operation of my invention, together with the apparatus which i now consider to represent the best, embodiment thereof; But I desire to have it understood that the apparatus shown is only illustrative and that the invention can he carried out by other means.

What I claim ashew and desire to secure by Letters Patent oi the United States, is:

1. Apparatus for llltilslll'lllg speed of rotation romprisinc; a rotation-counier, tilliilig: mechanism, electromagnetirally-operated mechanism for sinuiitaneously startin',,' and stopping said counter and timing meehanisnn and a plurality of switches arranged-in series for controlling said im-ehanlsm.

2. Apparatus for measuring the speed of a rotating elemeat, comprising: a rotalion-counter, an electromagnetic clutch for connecting said counter with said rotatinn -elcnient, timing mechanism. an electromagnetic releasing ments.

and stopping device therefor, and a switch for simultaneously closing and opening a circuit through said electromagnetic devices.

3'. Apparatus for measuring the speed of a rotating eie;

' ment. comprising -a rotation-counter, an electromagnetic clutch for connecting said counter with said rotating element. liming mechanism. an electromagnetic releasing and stopping device therefor, and a pluralityof switches in series with said electromagnetic devices.

4. Apparatus for measuring speed of rotation under constant load. comprising one or more load-indicating instrua rotation-counter. timing mechanism. electrical devil-es for simultaneously starting and stopping said rotation-counter and said timing mechanism; and a switch at each load-indicating instrument for controlling said dev'ees. i

5. Apparatus for measuring speed of rotation under constant load. comprising a rotation-counter, timing mechanism, electrical means for simultaneously starting-and stopping the same. and one or more load-indicatlngdevices controlling the circuit of said means.

ti. Apparatus for measuring speed of rotation under constant loath comprising a rotation-counter. timing mechanism. electrical means for simultaneously starting and stopping the same. one or more load-indicating devices, and a circuit-closer controlled by each deyice and in series with said electrical means.

in witness whereof. ihave hereunto set my hand this third day of ()eioher, 1903.

WALTER n. Lrrcnmnnn.

Witnesses 1 EDWARD WiLuAMsQ Jr., ilnnns ()nronn. 

